A high molecular polymer demulsifier, a preparation method and application thereof

Abstract

The application discloses a high-molecular polymer demulsifier and a preparation method and application thereof, and belongs to the technical field of oil exploitation. The high-molecular polymer demulsifier has a structure as shown in the formula (I): formula (I); wherein R1 and R2 are selected from H and CH3, R3 is a quaternary ammonium group, and n and m are integers of 50-120. The high-molecular polymer demulsifier has the characteristics of high dehydration rate, fast dehydration speed and small dosage, can be applied to demulsification of high-asphaltene and gummy crude oil, and is a high-efficiency demulsifier.

Description

Technical Field

[0001] This application relates to a polymer demulsifier, its preparation method, and its application, belonging to the field of petroleum extraction technology. Background Technology

[0002] As oilfield development enters its mid-to-late stages, the extensive use of surfactants and polymers in secondary and tertiary oil recovery processes leads to an increase in the emulsified oil content in the produced fluid, making oil-water separation more difficult. Early demulsifiers primarily used low-molecular-weight surfactants, such as anionic and nonionic surfactants. However, with increasing water content, the effectiveness of traditional demulsifiers became limited, failing to effectively treat these complex emulsions. This resulted in problems such as high dosage, poor efficacy, and the potential for secondary pollution. Therefore, high-molecular-weight polymer demulsifiers were developed to address these issues.

[0003] Polymer demulsifiers can reach the interfacial membrane of emulsions and adsorb onto their surface, reversibly agglomerating and flocculating the emulsion droplets together. As the emulsion droplets gradually flocculate, the loose flocs aggregate into larger droplets, and the large droplets achieve oil-water separation under the action of gravity.

[0004] Chinese invention patent CN113667055B discloses an acrylate-polymerizable quaternary ammonium salt copolymer demulsifier and its preparation method, which, as a polymer demulsifier, exhibits good demulsification effects. However, during the synthesis of polyoxypropylene polyoxyethylene ether, chain transfer occurs, making it difficult to increase the molecular weight of the demulsifier to obtain a polymer with a higher molecular weight. Consequently, it has poor compatibility with crude oils with high viscosity, and its effect is particularly poor in demulsifying crude oils with high asphaltene and gum content, limiting the application range of the demulsifier and lacking good universality.

[0005] Therefore, there is an urgent need to design a polymeric demulsifier suitable for demulsifying and dehydrating crude oil with high asphaltene and gum content. Summary of the Invention

[0006] The purpose of this invention is to provide a polymer demulsifier, its preparation method, and its application. It has the characteristics of high dehydration rate, fast dehydration speed, and low dosage. At the same time, it can adapt to the demulsification of crude oil with high asphaltene and gum content and has a wide range of applications.

[0007] According to one aspect of this application, a polymer demulsifier is provided having a structure as shown in formula (I):

[0008] Formula (I);

[0009] In this context, R1 and R2 are both selected from H and CH3, R3 is a quaternary ammonium group, and n and m are both integers between 50 and 120.

[0010] The polymeric demulsifier provided in this application contains aromatic rings, amide groups, and quaternary ammonium groups. The positively charged quaternary ammonium groups are strongly adsorbed onto the negatively charged oil-water interface through electrostatic attraction, thereby reducing the interfacial potential, weakening the electrostatic repulsion between small droplets, promoting droplet flocculation, and accelerating demulsification. The benzene ring inserts into the aromatic lamellar structure of asphaltenes or gums through π-π stacking, disrupting the stability of the interfacial film. The amide groups play a binding role between the water and oil interfaces, competitively replacing the original emulsion interface, and forming a dynamic hydrogen bond network with water molecules or interfacial polar groups (such as -COOH), accelerating the destruction of the interfacial hydration layer. The synergistic effect of the three groups can form a triple mechanism of electrostatic anchoring + hydrophobic insertion + hydrogen bond breaking, improving the demulsification effect of the demulsifier.

[0011] Optionally, the molecular weight of the polymer demulsifier is 10,000-30,000.

[0012] The polymer demulsifier in this application can reach a concentration of over 10,000, thereby generating a molecular-scale effect and a spatial synergistic effect of functional groups based on the synergistic effect of the three functional groups, resulting in a significant addition effect. The increase in polymer molecular weight is accompanied by an increase in the number of functional groups. The dense quaternary ammonium groups can generate a charge cluster effect, which multiplies the ability to neutralize interfacial charges; multiple phenyl anchor points form "molecular claws" that simultaneously destroy multi-point interfacial films and accelerate interfacial destruction; the amide groups in the long chain form a denser hydrogen bond network, which more thoroughly disintegrates the interfacial water molecule network, realizing the addition effect of the polymer on the functional groups.

[0013] Optionally, R3 has the following structure:

[0014] .

[0015] According to another aspect of this application, a method for preparing the above-mentioned polymer demulsifier is provided, comprising:

[0016] (1) Add acrylic monomers and polymerization inhibitors into the reactor, maintain the protective gas atmosphere inside the reactor, heat and stir, add aniline, and simultaneously purge and dehydrate with protective gas to obtain intermediates;

[0017] (2) Add the cationic polymer monomer and the amide obtained in step (1) to the reactor, stir evenly and add the initiator to react and obtain the polymer demulsifier.

[0018] The preparation method of the polymer in this application is simple, the raw materials are readily available, and it is easy to carry out industrial production, which can improve the preparation efficiency of demulsifier and reduce production costs.

[0019] Optionally, in step (1), the acrylic monomer is selected from acrylic acid and methacrylic acid.

[0020] Short-chain acrylic acid can avoid the steric hindrance of long-chain alkyl groups, allowing the amide groups formed with aniline to better form hydrogen bond networks with polar molecules in water or emulsions, thus accelerating water-oil separation.

[0021] Optionally, in step (1), the polymerization inhibitor is selected from any one of hydroquinone, p-benzoquinone, and hydroquinone monomethyl ether.

[0022] Optionally, in step (1), the mass ratio of the acrylic monomer to aniline is 1:(1.0-1.3).

[0023] Optionally, in step (1), the amount of the polymerization inhibitor added is 0.1%-1% of the total mass of acrylic monomers and aniline.

[0024] If the amount of polymerization inhibitor is too small, acrylic acid and aniline will undergo Michael addition reaction, and the conversion rate of amide will decrease. If the amount of polymerization inhibitor is too large, it will affect the polymerization reaction with cationic monomers in step (2).

[0025] Optionally, in step (2), the cationic polymerizing monomer is either acryloyloxyethyltrimethylammonium chloride or methacryloyloxyethyltrimethylammonium chloride.

[0026] Optionally, in step (2), the initiator is selected from either ammonium persulfate or azobisisobutyric acid hydrochloride.

[0027] Optionally, in step (2), the mass ratio of the amide to the cationic polymer monomer is 1:(0.8-1.4).

[0028] The reaction of cationic monomers with amides introduces cations into the polymer, which can strongly adsorb negatively charged oil-water interfaces, thereby reducing the interfacial potential, weakening electrostatic repulsion, promoting droplet flocculation, and accelerating demulsification. However, too few cationic monomers cannot play a sufficient role in adsorption and reducing interfacial potential, resulting in poor demulsification. On the other hand, the introduction of too many cations into the monomers causes the polymer to become overly hydrophilic, leading to the enrichment of molecules in the aqueous phase and making it impossible to effectively adsorb the oil-water interface, which will negatively affect the demulsification effect of the polymer.

[0029] Optionally, in step (2), the amount of initiator added is 0.3%-1.2% of the total mass of acrylic monomers and aniline.

[0030] Optionally, in step (1), the heating temperature is 120°C and the reaction process is carried out at 120-130°C for 4-5 hours; in step (2), the heating temperature is 70°C and the reaction process is carried out at 70°C for 3-4 hours.

[0031] According to another aspect of this application, the application of the above-mentioned polymeric demulsifier or the polymeric demulsifier prepared by the above-mentioned preparation method in the process of demulsification and dehydration of produced crude oil is provided.

[0032] The beneficial effects of this application include, but are not limited to:

[0033] 1. The polymeric demulsifier of this application contains aromatic rings, amide groups, and quaternary ammonium groups. The positively charged quaternary ammonium groups are strongly adsorbed onto the negatively charged oil-water interface through electrostatic attraction, thereby reducing the interfacial potential, weakening the electrostatic repulsion between small droplets, promoting droplet flocculation, and accelerating demulsification. The introduction of benzene rings increases the aromaticity and polarity, and inserts into the aromatic lamellar structure of asphaltenes or gums through π-π stacking, promoting the movement of highly active asphaltenes micelles or aggregates towards the single molecule direction, reducing the activity of asphaltenes and gums, and destroying the stability of the interfacial film. The amide groups play a binding role between the water and oil interfaces, competitively replacing the original emulsion interface, and forming a dynamic hydrogen bond network with water molecules or interfacial polar groups (such as -COOH), accelerating the destruction of the interfacial hydration layer. The synergistic effect of the three groups can form a triple action mechanism of electrostatic anchoring + hydrophobic insertion + hydrogen bond disintegration, improving the demulsification effect of the demulsifier.

[0034] 2. The polymer demulsifier of this application, through the setting of reaction method steps and conditions, results in a polymer demulsifier with a high molecular weight, where longer linear molecular chains will become entangled and form a network structure at the interface, physically coating asphaltene, gum and other natural emulsifier particles, and accelerating their detachment from the interface.

[0035] 3. The polymer demulsifier of this application enhances the demulsification effect of the three groups in the larger polymer, increases the distribution density of quaternary ammonium salt, increases the bridging density to form large-scale flocs, and weakens the charge shielding effect of quaternary ammonium salt in high-salt environment. At the same time, it achieves multi-point distribution of phenyl and amide groups, which greatly improves the demulsification effect.

[0036] 4. The polymeric demulsifier of this application uses aniline and acrylic acid to form an amide body, introducing a benzene ring structure. In crude oil with high asphaltenes and gum content, the presence of natural emulsifiers such as asphaltenes and gums can stabilize the crude oil emulsion and hinder the demulsification process. However, the activity of asphaltenes and gums depends on their degree of aggregation. The polymeric demulsifier of this application introduces a benzene ring structure, which increases the aromaticity and polarity, and promotes the movement of highly active asphaltenes from micelles or aggregates to single molecules. A single asphaltenes molecule is not enough to stabilize the crude oil emulsion, thereby reducing the activity of asphaltenes and gums, playing a solubilizing role, and making it easier to demulsify.

[0037] 5. The preparation method of the polymer demulsifier of this application is simple, the raw materials are readily available, and it is easy to carry out industrial production. The prepared polymer demulsifier has low dosage, high demulsification rate, fast dehydration speed, is not easily replaced by emulsifiers, and has a long-lasting demulsification effect. It is widely used in the treatment of oilfield produced fluids. Attached Figure Description

[0038] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0039] Figure 1 This is a diagram of the polymer demulsifier 1#GPC from Example 1 of this application.

[0040] Figure 2 The infrared spectrum of polymer demulsifier 1# in Example 1 of this application is shown. Detailed Implementation

[0041] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0042] Unless otherwise specified in the examples, the conditions shall be performed in accordance with conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials or instruments used are conventional products that can be purchased commercially.

[0043] Example 1

[0044] A method for preparing a polymer demulsifier, comprising:

[0045] (1) Add 72g of acrylic acid and 1g of hydroquinone to the reaction vessel, purge with nitrogen three times to maintain nitrogen protection in the vessel, stir and heat to 120℃, add 93g of aniline, and react at 120-130℃ for 4.5h. Nitrogen is used to purge the water generated during the reaction to accelerate the reaction and form an intermediate. The reaction equation is as follows:

[0046]

[0047] (2) Add 147g of the amide formed in step (1) and 194g of acryloyloxyethyltrimethylammonium chloride to the reaction vessel at room temperature, stir evenly, add 3.2g of azobisisobutyric acid hydrochloride, and react at 70℃ for 3.5h. The reaction equation is as follows:

[0048]

[0049] Example 2

[0050] A method for preparing a polymer demulsifier, comprising:

[0051] (1) Add 86g of methacrylic acid and 1.1g of p-benzoquinone to the reaction vessel, purge with nitrogen three times, maintain nitrogen protection in the vessel, stir and heat to 120℃, add 93g of aniline, and react at 120-130℃ for 4h. Nitrogen gas is used to purge the water generated during the reaction to accelerate the reaction and form an intermediate. The reaction equation is as follows:

[0052]

[0053] (2) Add 161g of the amide formed in step (1) and 194g of acryloyloxyethyltrimethylammonium chloride to the reaction vessel at room temperature, stir evenly, add 3.5g of azobisisobutyric acid hydrochloride, and react at 70℃ for 4h. The reaction equation is as follows:

[0054]

[0055] Example 3

[0056] A method for preparing a polymer demulsifier, comprising:

[0057] (1) Add 72g of acrylic acid and 1g of hydroquinone monomethyl ether to the reactor, purge with nitrogen three times, maintain nitrogen protection in the reactor, stir and heat to 120℃, add 93g of aniline, and react at 120-130℃ for 5h. At the same time, purge with nitrogen to remove the water generated in the reaction, accelerate the reaction, and form an intermediate. The reaction equation is as follows:

[0058]

[0059] (2) Add 147g of the amide formed in step (1) and 208g of methacryloyloxyethyltrimethylammonium chloride to the reaction vessel at room temperature, stir evenly, add 3g of azobisisobutyric acid hydrochloride, and react at 70℃ for 3h. The reaction equation is as follows:

[0060]

[0061] Example 4

[0062] A method for preparing a polymer demulsifier, comprising:

[0063] (1) Add 72g of acrylic acid and 0.9g of hydroquinone to the reactor, purge with nitrogen three times to maintain nitrogen protection in the reactor, stir and heat to 120℃, add 75g of aniline, and react at 120-130℃ for 4.5h. Nitrogen is used to purge the water generated during the reaction to accelerate the reaction and form an intermediate. The reaction equation is as follows:

[0064]

[0065] (2) Add 132g of the amide formed in step (1) and 194g of methacryloyloxyethyltrimethylammonium chloride to the reaction vessel at room temperature, stir evenly, add 2.8g of ammonium persulfate, and react at 70℃ for 3.5h. The reaction equation is as follows:

[0066]

[0067] Example 5

[0068] The difference from Example 1 is that in step (2), the amount of amide added is 147g and the amount of acryloyloxyethyltrimethylammonium chloride added is 105g.

[0069] Example 6

[0070] The difference from Example 1 is that in step (2), the amount of amide added is 208g and the amount of acryloyloxyethyltrimethylammonium chloride added is 132g.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that the amidation of acrylic acid and aniline is not carried out; only the polymerization reaction of acrylic acid and acryloyloxyethyltrimethylammonium chloride is carried out. The specific process is as follows: 42.55g of dipropylene glycol methyl ether and 28.37g of deionized water are weighed in a three-necked flask and mixed evenly to prepare an ether-water mixed solvent. Then, 11.88g of butyl acrylate, 14.85g of methacryloyloxyethyltrimethylammonium chloride in the form of an 80% aqueous solution, 1.25g of acrylamide, 1g of PEG-20000 and 0.1g of disodium ethylenediaminetetraacetate are added to the ether-water mixed solvent, stirred and dissolved, and mixed evenly. After purging with nitrogen for 30min to remove oxygen, 0.2g of azobisisobutyronitrile is added. Then, the total reaction solution is heated to 55°C and stirred for 8h. After the reaction is completed, the product is cooled and discharged to obtain the demulsifier product.

[0073] Comparative Example 2

[0074] The difference from Example 4 is that it uses methacryloyloxyethyltrimethylammonium chloride as the main component, compounded with sodium acrylate, acrylamide, polyoxyethylene polyoxypropylene polyether, and polyaluminum chloride. The specific preparation method is as follows:

[0075] (1) Place 5% by mass of methacryloyloxyethyltrimethylammonium chloride in a reaction vessel, heat to 45-50℃ under nitrogen protection and stir continuously, add 1% by mass of acrylamide, stir and react for 6 hours to obtain polymer reaction solution;

[0076] (2) Add 2% sodium acrylate by mass to the polymer reaction solution obtained in step (1), stir and react for 2 hours to obtain reaction solution 2;

[0077] (3) Add 4% by mass of polyoxyethylene polyoxypropylene polyether to the reaction solution 2 obtained in step (2), stir and react for 2 hours to obtain reaction solution 3;

[0078] (4) Add 5% by mass of polyaluminum chloride to the reaction solution 3 obtained in step (3), stir and react for 1 hour, and cool to room temperature (15-25℃) to obtain the demulsifier for treating oily emulsion wastewater.

[0079] The mass of methacryloyloxyethyltrimethylammonium chloride is 194g, and the volume ratio of methacryloyloxyethyltrimethylammonium chloride, sodium acrylate, acrylamide, polyoxyethylene polyoxypropylene polyether and polyaluminum chloride is 1.2:1.1:1:1.3:1.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that aniline is replaced with 3,3-dimethyl-2-butylamine.

[0082] Test Example 1

[0083] Crude oil demulsification experiment at a joint station of Shengli Oilfield

[0084] Experiments were conducted on produced oil samples (asphaltene content 14%) from a joint station in Shengli Oilfield. The demulsification performance of each reagent group was tested under the same temperature and dosage conditions. This included samples of the demulsifier currently in use at the joint station (polyether-type demulsifier, molecular weight 4000). The demulsifiers obtained in Examples 1-6 were designated as 1#, 2#, 3#, 4#, 5#, and 6#, while the demulsifiers obtained in Comparative Examples 1-3 were designated as D1#, D2#, and D3#. The field oil sample had a water content of 33%, a dehydration temperature of 55℃, and a test volume of 80 mL.

[0085] The test results for each drug are shown in Table 1:

[0086] Table 1 Dehydration data of demulsifier

[0087]

[0088] As shown in Table 1, the polymer demulsifiers 1#-6# provided in Examples 1-6 have high dehydration rates, all meeting the requirement of >90% on-site dehydration rate. Among them, polymer demulsifier 1# has the best effect, achieving a dehydration rate of 95.1% for crude oil with high asphalt content, which is better than conventional polyether demulsifier products on-site.

[0089] Based on the difference in effects between Comparative Example 1 and Example 1, it can be seen that the benzene ring inserts into the aromatic lamellar structure of asphaltenes or gums through π-π stacking, thereby disrupting the stability of the interfacial film; the amide groups play a binding role between the water and oil interfaces, competing to replace the original emulsified interface.

[0090] Based on the differences in effects between Examples 5, 6 and 1, it can be seen that when amide is in excess, a large amount of amide does not participate in the polymerization reaction and does not polymerize with quaternary ammonium cations to form cationic polymers. Instead, it exists in the form of amide monomers. Furthermore, compared with Example 1, the monomers present do not adsorb onto the oil-water interface by electrostatic attraction during the demulsification process, resulting in a relatively low demulsification rate.

[0091] Based on the difference in effects between Comparative Example 2 and Example 4, it can be seen that the demulsification effect of the polymer formed by using methacryloyloxyethyltrimethylammonium chloride as a monomer is better than that of the compound product using dimethyl diallyl ammonium chloride as a monomer. This shows that polymer-type demulsifiers are more likely to disrupt the stability of emulsions.

[0092] Based on the difference in effects between Comparative Example 3 and Example 1, it can be seen that introducing a benzene ring structure into the polymer can increase the aromaticity and polarity of the environment surrounding the asphaltene in crude oil with high asphaltene content, promote the movement of highly active asphaltene micelles or aggregates towards the single molecule direction, and facilitate demulsification.

[0093] Figure 1 The image shows the GPC diagram of polymer demulsifier 1#. The molecular weight of polymer demulsifier 1# provided in Example 1 was determined, and the weight-average molecular weight can reach 19509.

[0094] Figure 2 Infrared spectrum of polymer demulsifier #1, 3400 cm⁻¹ -1 The NH absorption peak of the amide is at 1600 cm⁻¹. -1 The peak for the NH bending vibration of amides is 1650 cm⁻¹. -1 This is the C=O absorption peak in acrylic acid, 770 cm⁻¹. -1 The absorption peak for monosubstituted benzene rings is at 1725 cm⁻¹. -1 The absorption peak for C=O in acryloyloxyethyltrimethylammonium chloride is 3050 cm⁻¹. -1 This is the absorption peak of quaternary ammonium.

[0095] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A polymer demulsifier, characterized in that, It has a structure as shown in equation (I): Equation (I); Among them, R1 and R2 are both selected from H and CH3, and R3 has the following structure: Both n and m are integers between 50 and 120.

2. The polymer demulsifier according to claim 1, characterized in that, The molecular weight of the polymer demulsifier is 10,000-30,000.

3. A method for preparing a polymer demulsifier as described in any one of claims 1-2, characterized in that, include: (1) Add acrylic monomers and polymerization inhibitors into the reactor, maintain the protective gas atmosphere inside the reactor, heat and stir, add aniline, and simultaneously purge and dehydrate with protective gas to obtain intermediates; (2) Add the cationic polymer monomer and the intermediate obtained in step (1) to the reactor, stir evenly and add the initiator to react and obtain the polymer demulsifier.

4. The method according to claim 3, characterized in that, In step (1), the acrylic monomer is one of acrylic acid and methacrylic acid; and / or The polymerization inhibitor is one of hydroquinone, p-benzoquinone, and hydroquinone monomethyl ether.

5. The method according to claim 3, characterized in that, In step (1), the mass ratio of the acrylic monomer to aniline is 1:(1.0-1.3). The amount of the polymerization inhibitor added is 0.1%-1% of the total mass of acrylic monomers and aniline.

6. The method according to claim 3, characterized in that, In step (2), the cationic polymerization monomer is either acryloyloxyethyltrimethylammonium chloride or methacryloyloxyethyltrimethylammonium chloride; The initiator is either ammonium persulfate or azobisisobutyramidine hydrochloride.

7. The method according to claim 3, characterized in that, In step (2), the mass ratio of the intermediate to the cationic polymer monomer is 1:(0.8-1.4). The amount of initiator added is 0.3%-1.2% of the total mass of the intermediate and the cationic polymer monomer.

8. The method according to claim 3, characterized in that, In step (1), the heating temperature is 120℃, and the reaction process is carried out at 120-130℃ for 4-5 hours; and / or In step (2), the reaction process is carried out at 70℃ for 3-4 hours.

9. The application of the polymer demulsifier according to any one of claims 1-2 or the polymer demulsifier prepared by any one of claims 3-8 in the process of demulsification and dehydration of produced crude oil.

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